Prismatic telescope with rightangled isosceles reflecting prisms



May 22, 1934- E. LANGENHAGEN Er AL l 1,959,538y

PRIsMATIc TELESCOPE WITH RIGHT ANGLED ISOSCELES REFLECTING PRISMS Filed Aug. l2. 1932 Patented May 22, 1934 UNITED STATES PATENT 'OFFICE4 1,959,538 PRISMATIC `TELESCOPE WITH RIGHT- ANGLED riusMs ISOSCELES RE FLE CAT IN G Ernst Langenhagen and Robert Mec-hau. Jena,

Germany, assignor to the firm Carl Zeiss, Jena,

-Germany Application August 12, 1932, Serial No. 628,556 In Germany August 17, 1931 whole of the hypotenuse surface of the prismv rests on a plane surface. It has been proved however, that this kind of prism support gives rise to tensions in the prism. Whenworking the seat in the usual manner, its support surface will not be exactly plane but slightly vaulted (hollow).

- which means that the hypotenuse surface'of the prism is supported only at two ends. As a conseu quence, when pressed against its seat, the prism has to suffer-the said tensions.

The invention aims `at avoiding these tensions by so supporting the prism that only that part of its hypotenuse surface which lies in the inid- .0 die between the two reflecting surfaces rests against the prism seat. f

A support of .this kind is attained forI instance by so constructing the prism seat that that part of this seat against which the hypotenuse surfacerests has an elevation. This elevation is obtained for instance by suitably working the prism seat.

A vaulted form of the seat surface will especially answer the purpose.

If it is desired to work the seat in the same I0 manner as hitherto, that is to say by aiming at a plane support surface (which, as said above, is

however not attained completely), an elevation for avoiding the tensions in the prismmay be provided either by placing a special body,.for instance a tinfoil plate, on. the prism seat or by providing a recess ln the hypotenuse surface in the middle between the two reflecting surfaces and placing in this recess a body. preferably a wire of such thickness that the prism lies against this The prism may be supported in a very convenlent manner in the sense of the invention also byelevating part of it, iary means. The accompanying drawing illustrates live constructional examples of the invention. Figures l and 2 represent, partly in a section, partly in elevation, and partly in a plan view, partof a prismaticV binocular telescope with Porro prisms. lo In these two figures, the lens members as well as the caps are left away. In Figure 2 also the prisms are not`shown. Figures 3, 4 and 5 represen/t partial sections in elevation of three other constructional forms of a telescope of the said Il kind. Figure 6 represents a reflecting prism althus dispensing with auxiltered for the purposes of the present invention.

. In Figures l and 2, a is a telescope tube the seat bof which supports two Porro prisms c and d. The

support surfaces bl and b2 held by the seat b are plane. In the middle of -these support surfaces are fixed tinfoil plates e1 and c2, respectively. against which the prisms c and d lie with those parts of their hypotenuse surfaces cl and d1, respectively, which are opposite the truncating sur` faces c2 and d2 in the' direction of the pressure ex'- 65 cried upon the prisms by springs f1 and f2 when these prisms are fixed in the tube.

The constructional form according to Figure 3 differs from those according to Figures 1 and 2 only by the fact that each support surface con- 'lo -ssts 'of three plane parts the central part b of which is parallel to the hypotenuse surface of the appertaining prism, 'and that the two lateral parts b" and b'" and the respective hypotenuse surfaces embrace angles. In this constructional 'l5 form. each prism rests only against the middle part b' of the support surface.

in the constructional form according to Figure 4. each support surface is vaulted and this in such a way that only' the central part of the l0 vault supports the appertaining prism.

In the constructional form according to Figure 5 use is made of prisms c and d whose hypotenuse surfaces cl and d1, respectively, have recesses c3 and d3, respectively, in their middle parts. 85 In these recesses are disposed wires gl and g, r spectively, vthese wires transmitting to the prism seat b the pressure exerted upon the prisms fixed in the tube a.

The prism c according to Figure 6 is to be placed on a plane seat. for instance as illustrated in Figure 5. This prism c has a glass plate h cemented to that part of Aits hypotenuse surface cl which is opposite the truncating surface c2 in the direction of the pressure exerted upon the prism fixed in the telescope tube. The prism and the plate h may be integral.

We claimz` 1..A prismatic telescope. comprising two telescope tubes, right-angled isosceles reecting prisms. each reflecting prism resting against a supporting part of the appertaining tube only with that part of its hypotenuse surface which lies in prisms, each reflecting prism resting against a supporting part of the appel-taining tube, this supporting part being an elevation touching the hypotenuse surface of the appertaining prism at that part which lies between the reflecting surfaces of the prism, and means pressing each prism against the appertaining elevation, these means acting only against that part of the prism which is adjacent to the line of intersection of the two reflecting surfaces.

3. A prismatic telescope, comprising two telescope tubes, right-angled isosceles reflecting prisms, each reflecting prism resting against a supporting part of the appertaining tube, this supporting part being an elevation which is irepresented by a vaulted surface and touches the hypotenuse surface of the appertaining prism at that part which lies between the reflecting surfaces of the prism, and means pressing each prism against the appertaining vaulted surface, these means acting only against that part of the prism which is adjacent tothe line of intersection of the two reflecting surfaces.

4. A prismatic telescope, comprising two telescope l tubes, right-angled isosceles reiiecting prisms, each reflecting prism resting against am supporting part of the appertaining tube with its hypotenuse surface, the supporting part being anJ intermediate body placed between the tube and that part of the hypotenuse surface of the appertaining prism which lies in the middle between the reflecting surfaces of this prism, and means for pressing the prism against the tube, these means acting only against that part of the prism which is adjacent to the line of intersection oi' the two: iiecting surfaces.

5. A prismatic telescope, comprising two telescope tubes, right-angled isosceles reflecting prisms, each reflecting prism having a recess in that part of its hypotenuse surface which iles in the middle between its two reflecting surfaces,

veach reflecting prism resting against a supporting part of the appertaining tube. this supporting part being an intermediate body carried by the tube and engaging the said recess, and means for pressing the prism against the tube, these means acting only against that part of the prism which is adjacent to the line of intersection of the two reflecting surfaces.

ERNST LANGENHAGIN. ROBERT MECHAU. 

